Figure 5 - Michaelis Menten Graph of Ethanol (pH 9.0) Representing the Velocity versus Substrate Concentration. Different concentrations of ethanol were used, and the absorbance reading taken through enzyme kinetics. The velocity was calculated through the conversion of the slope of the data points to abs/min. K_m was found to be 5.76×〖10〗^(-3) M, V_max 1.71×〖10〗^(-3) M/min, K_cat 2.85×〖10〗^(-2) 〖min〗^(-1), and K_cat/K_m 4.94 〖min〗^(-1) M^(-1).
Figure 5 - Michaelis Menten Graph of Ethanol (pH 7.2) Representing the Velocity versus Substrate Concentration. Different concentrations of ethanol were used, and the absorbance reading taken through enzyme kinetics. The velocity was calculated through the conversion of the slope of the data points to abs/min. K_m was found to be 7.66×〖10〗^(-4) M, V_max 8.84×〖10〗^(-4) M/min, K_cat1.47×〖10〗^(-2) 〖min〗^(-1), and K_cat/K_m= 19.2 〖min〗^(-1) M^(-1).
Table 4- Michaelis-Menten Kinetic Data [Original Experiment]
Buffer KM (mM) Vmax (µM/min) Kcat (min-1) Kcat/KM(min-1 M-1)
7.2 0.000766 0.000884 0.0147 19.2
8.5 0.00248 0.00231 38.4 155
9.0 0.00576 0.00171 0.0285 4.94
*Literature 7.05 26 1.03 N/A N/A
*Literature 8.1 18.5 0.5583 N/A N/A
*Literature 8.9 ~10 0.383 N/A N/A
*Literature values taken from Dickinson4 The Km data from table 4 suggests that a buffer of 7.2 has the highest affinity of ADH to the substrate, ethanol. This experimental data does not correlate with what was found in the literature in either values or trends of
Five cuvettes provided by the instructor were used during the experiment. The transmittance on the spectrophotometer was zeroed on an empty chamber and it was set at a wavelength of 486 nm. There was only one blank containing 0.5 mL of enzyme solution (catechol oxidase) and 4.5 mL of pH 6 buffer. The blank was prepared at the beginning of the experiment and used throughout the experiment. The blank was used to zero the absorbance on the spectrophotometer before each experimental trial. The experimental cuvettes contained 0.5 mL of catechol oxidase (enzyme), 0.5 mL of 5mM catechol (substrate), and 4.0 mL of pH 6 buffer for a total of 5.0 mL of solution. The results for the experimental trials were obtained after 0 seconds, 30 seconds, 1minute and 30 seconds, 3 minutes, and 5 minutes in five different reactions. The enzyme and substrate were obtained using a micropipette, and the pH was measured using a 10mL pipet. Each experimental trial was carried out twice for a total of ten experimental
The aim of the study is two-fold: to study the rate of absorbance with increasing concentration of glucose, and to measure the activity of enzyme yeast invertase on sucrose. In task 1, the product formation was measured using 3, 5-dinitrosalicyclic acid that reacts with glucose leading to a change in colour from yellow to reddish brown. In task 2, the enzyme kinetics of yeast invertase on sucrose was studied. The absorbance values of the corresponding volumes of the solutions were measured using a spectrophotometer. Michaelis-Menten curve and Lineweaver-Burk Plot were made in order to estimate the values of Vmax and Km
Lab six requires students to observe the effects of pH and enzyme concentration on catecholase activity. Enzymes are organic catalysts that can affect the rate of a chemical reaction depending on the pH level and the concentration of the enzyme. As pH comes closer to a neutral pH the enzyme is at its greatest effectiveness. Also at the absorbance of a slope of 0.0122 the enzyme is affected greatly. The pH effect on enzymes can be tested by trying each pH level with a pH buffer of the same pH as labeled as the test tube and 1mL of potato juice, water, and catechol. This is all mixed together and put in the spectrophotometer to test how much is being absorbed at 420nm. As the effect on enzyme concentration can be tested almost the same way. This part of the exercise uses different amounts of pH 7-phosphate buffer and potato juice, and 1mL of catechol mixed together in a test tube. Each substance is put in the spectrophotometer at a wavelength set tot 420nm. The results are put down for every minute up to six minutes to see how enzyme concentration affects reaction rate. The results show that the pH 8 (0.494) affects the enzyme more than a pH of 4 (0.249), 6 (0.371), 7 (0.456), and 10 (0.126). Also the absorbance is greatest at a slope of 0.0122 with test tube C that has more effect on the reaction rate, than test tube A, B, and D.
These results shown from this experiment led us to conclude that enzymes work best at certain pH rates. For this particular enzyme, pH 7 worked best. When compared to high levels of pH, the lower levels worked better. The wrong level of pH can denature enzymes; therefore finding the right level is essential. The independent variable was the amount of pH, and the dependent being the rate of oxygen. The results are reliable as they are reinforced by the fact that enzymes typically work best at neutral pH
Background and Introduction: Enzymes are proteins that process substrates, which is the chemical molecule that enzymes work on to make products. Enzyme purpose is to increase the rate of activity and speed up chemical reaction in a form of biological catalysts. The enzymes specialize in lowering the activation energy to start the process. Enzymes are very specific in their process, each substrate is designed to fit with a specific substrate and the enzyme and substrate link at the active site. The binding of a substrate to the active site of an enzyme is a very specific interaction. Active sites are clefts or grooves on the surface of an enzyme, usually composed of amino acids from different parts of the polypeptide chain that are brought together in the tertiary structure of the folded protein. Substrates initially bind to the active site by noncovalent interactions, including hydrogen bonds, ionic bonds, and hydrophobic interactions. Once a substrate is bound to the active site of an enzyme, multiple mechanisms can accelerate its conversion to the product of the reaction. But sometimes, these enzymes fail or succeed to increase the rate of action because of various factors that limit the action. These factors can be known as temperature, acidity levels (pH), enzyme and/or substrate concentration, etc. In this experiment, it will be tested how much of an effect
The purpose of this experiment was to record catalase enzyme activity with different temperatures and substrate concentrations. It was hypothesized that, until all active sites were bound, as the substrate concentration increased, the reaction rate would increase. The first experiment consisted of five different substrate concentrations, 0.8%, 0.4%, 0.2%, 0.1%, and 0% H2O2. The second experiment was completed using 0.8% substrate concentration and four different temperatures of enzymes ranging from cold to boiled. It was hypothesized that as the temperature increased, the reaction rate would increase. This would occur until the enzyme was denatured. The results from the two experiments show that the more substrate concentration,
The independent variable in this investigation is pH. Each individual enzyme has it’s own pH characteristic. This is because the hydrogen and ionic bonds between –NH2 and –COOH groups of the polypeptides that make up the enzyme, fix the exact arrangement of the active site of an enzyme. It is crucial to be aware of how even small changes in the
The motive of this lab is to attain a better understanding of enzyme activity by timing chemical reactions in certain temperatures and pH levels. Enzymes act as catalysts that help speed up reactions. Without these enzymes chemical reactions in metabolism would be backed up. There are two factors that affect an enzyme’s reaction rate: temperature and pH levels. In this label we will be testing different pH levels and temperatures to see which ones cause the most reactions.
J. Moldovan & B. Nilson, (2010), Lab 4 – Enzyme Kinetics, UBCO BIOL/BIOC 393, UBC Vista accessed Monday, November 8th, 2010.
In this experiment we tested the effects that enzymes and substrate have on chemical reaction rates, which is the rate at which chemical reactions occur.. This experiment tested how different concentrations of enzyme and substrate affected the light absorption measurements on a spectrophotometer. The experiment also tested how temperature affected the light absorption, and in a separate test, the effect of the enzyme inhibitor hydroxylamine was also tested. In the first test conducted, 3 different concentrations of enzyme, and three different concentrations of substrate were measured in a spectrophotometer. For the enzyme and the substrate, the measurements got higher as the concentrations were higher, but the over measurements of the substrate were smaller than those of the enzyme. In the second test conducted, the medium concentration enzyme was tested under the temperatures; 4°C, 23°C, 37°C, and 60°C. The measurements in this test got higher as the temperature got higher, but did the measurements under 4°C were overall significantly higher than the other temperature measurements. Lastly, the last test conducted showed that the measurements of the substance with 0 and 1 drop of hydroxylamine inhibitor went up, but the measurements of the enzyme with 5 drops of hydroxylamine inhibitor stayed rather low and did not change much. In conclusion, these experiments showed that chemical reaction rates are sped up with higher concentrations of enzyme, substrate,
Enzymes are biological catalysts. They work by lowering the activation energy needed to initiate a chemical reaction. Enzymes work within an optimal temperature and optimal pH. Enzymes are highly specific for a single substrate. The Enzyme is usually much larger in size than the substrate it binds to. In some cases, an enzyme requires something called a cofactor to begin the chemical reaction. There were four different experiments that were executed in the enzyme lab. Experiment 7.1, the first experiment, was performed to test the effect of temperature on enzymatic
Background: Enzymes are proteins that increase the rate of reaction by lowering the activation energy. When an enzyme binds to a specific substrate, an enzyme substrate complex is formed, allowing for the reaction to take place over less time. Since the enzyme is recyclable, the reaction produces a product and the unaltered enzyme. Catalase is the enzyme used specifically for the decomposition of hydrogen peroxide. Furthermore, the amount of substrate used can be determined by measuring the amount of product formed in the reaction. If the amount of product formed over time is graphed, the graph will prove the rate of reaction to decrease over time as the availability for a substrate and enzyme to bind decreases. The initial velocity of an enzyme-catalyzed reaction is constant because the number of substrate molecules at the beginning of a reaction is typically vastly greater than the number of enzymes, causing the rate to be determined by the characteristics of the enzyme. When the substrate concentration decreases to a certain point, when enzymes and substrates do not easily collided in the specific manner to form the enzyme-substrate complex, the rate of reaction will decrease.
Saturation of substrates was a phenomenon that was observed in Part II of the experiment. This was referenced from later in the discussion. When the enzyme activity from this experiment was compared to Enoch’s work, (Enoch) it was stated that he found that in certain liver cells of rats, enzyme activity would stop suddenly. The study proposed that the lower Enoch dropped the substrate concentration within these cells, the less activity he could record. This proved to both his data and to the date from this experiment that the substrate was necessary for catalysis, because as enzyme concentration rose, substrates bound more quickly to the active site of an enzyme. Once all substrates in the mixture were changed to products, the enzyme was stationary because it had no more substrate to catalyze. This meant that in order for the reaction to continue, substrate concentration had to increase.
The experiments involved PH buffers of different pH were added to potato juice, water, and the enzyme catecholase. The mixture was then subjected to spectrophotometer at a wavelength of 420nm taking the absorbance readings. In the second experiment, a phosphate buffer of PH 7.0 was used in different measures together with different measurement of potato juice and the enzyme catecholase then subjected to the spectrophotometer at a wavelength of 420nm. The data collected inform of table and analyzed using descriptive statistics such as line graph and later interpreted, showing that PH and enzyme concentration do affect the rate of enzyme reaction
The hypothesis is as the substrate concentration has an increase so will the reaction of velocity if the amount of enzyme is kept constant.